Safety-cushion for elevators



,No Model.) v

W. E. NIGKERSON. SAPETY'GUSHION FOR ELEVATORS.

Patented Aug. 20, 1889.

. 1 WITNEEEESF g UNITED STATES PATENT OFFICE.

\VILLIAM E. NICKERSON, OF CAMBRIDGE, MASSACHUSETTS.

SAFETY-CUSHION FOR ELEVATORS.

SPECIFICATION forming part of Letters Patent No. 409,486, dated August20, 1889.

Application filed May 15, 1889. Serial No. 810,881. (No model.)

To all whom, it may concern.-

Be it known that I, WILLIAM EMERY N 101(- ERSON, of Cambridge, in thecounty of Middlesex and State of Massachusetts, have in vented certainnew and useful Improvements in Non-Rebounding Safety-Cushions forElevators, of which the following, taken in connection with theaccompanying drawings, is a specification.

My invention relates to elevators, its object being to lessen the dangerto life and property in the event of the accidental fall of thecarriage.

It consists in placing at the bottom of the well-room a number of thinplatforms, or their equivalent, arranged in a vertical series, eachplatform being separated from the one above and the one below it by athin space, and being supported in its normal position by pins or pegsof sufficient strength to sustain its weight, but adapted to give waywhen subjet-ted to a considerable increase of pressure, whereby thevelocity of the falling carriage is gradually checked, principally bythe inertial resistance of the platforms acting successively, andincidentally by the elastic resistance of the thin layers of air, (inbeing squeezed out from between the platforms,) and the successiveresistances to shearing or bending of the pins by which the platformsare normally supported. The action of this mechanism is such that norebound will occur.

The so-ealled elevator air-cushion heretofore in use, consisting of astrong air-tight box which the carriage nearly fills, is design ed togradually check the velocity of the falling carriage by the elasticresistance of the inclosed air alone. Great difficulties in the way ofsuccessful operation of this device have presented themselves, for if,on the one hand, the carriage too nearly fills the air-pit the reboundcaused by the expansion of the highlycompressed air is disastrous, andif, on the other hand, the carriage fits the pit too loosely sufficientcompression is not obtained to properly check its velocity. Experiencehas proved that the proper adjustment is not easily obtained. Further,when air alone is relied upon to check the falling carriage the air-pit,to work successfully with great velocities, must be of great depth, forthe carriage advances far into it before any sensible checking ocours,and with living freight the distance in which a falling carriage isbrought to rest must not be less under any circumstances than one-tenththe space fallen through. There is danger, also, with the ordinaryair-cushion of the walls of the air-pit giving way or the bottom of thecarriage yielding upward under the great strain incurred.

My invention is intended to supply a cheap and efiicient remedy forthese difficulties, and is set forth in the following specification andillustrated in the accompanying drawings, in which- Figure 1 shows,partly in elevation and partly in vertical section, such parts of anelevator as are necessary to illustrate my invention. Fig. 2 is a planof my device.

A, Fig. 1, represents an elevator-carriage; B, the well-posts, and B theguides.

C 0 represent thin wooden platforms or disks placed at the bottom of theWell-room and arranged in a vertical series, each being separated fromthe others by the spaces C C. These platforms 0 C are each held in theirnormal positions, as shown in Figs. 1 and 2, by pins or pegs of acertain determined strength, and shown by C 0 Figs. 1 and 2. Some ofthese pins are driven into the guideposts and others into separate postsprovided for the purpose, as shown by B B Fig. 2.

It will be observed, by referring to Fig. 2, that when the platform C isforced downward, so as to break or bend the pins 0 G they will have roomto pass between the edge of the platform and the posts in B B by lyingin the grooves Z) b, and in B B by lying beside the guides B' B.

c, Fig. 2, is -a space of liberal dimensions between the edges of theplatforms and the sides of a pit, in which they are shown as located,and is for the purpose of allowing a ready escape of the air between theplatforms when it shall be forced out.

The platforms are made, preferably, of two layers of thin boards, thegrain of the 'WOOCl in one layer being at right angles to that of theother layer. They may be made of cheap lumber, and as many used asdesired, according to the height of the building, and their combinedweight may much exceed that of the carriage. The pins may be of iron orwood. In the event of the precipitation of the carriage no one of theplatforms is heavy enough to give it a shock; but their combinedinertia,

acting successively, co-operating with the cushioning effect of the thinlayers of air and the resistance of the pins, will bring it gradually torest without rebound, as the air between the platforms on being squeezedout escapes freely, and so cannot throw the carriage upward again.

In the drawings the platforms are represented as being in a roomy pit,the earth around it being represented by D. No pit, however, isnecessary to the successful operation of my device, and in buildingswhere the carriage does not descend into the basement the platforms maybe arranged openly under the elevatorshaft, there being of course anaperture in the floor to allow the carriage to descend upon them.

In my device the carriage feels the strong checking action of thecushion from the first instant of contact with the uppermost platform,and the space in which it mustgradually come to rest is equal to the sumof all the inter-air spaces 0' G. If considered desirable, a smallquantity of straw or other similar substance may be loosely spread inthe air-space between the platforms to soften the concussion and preventthe too rapid escape of the air.

I claim In a safety-cushion for elevators, a series of air-spacedplatforms supported normally on pins, said pins being adapted to yieldto increased pressure, substantially as and for the purpose set forth.

In testimony whereof I have signed my name to this specification, in thepresence of two subscribing witncsses, on this 13th day of May, A. D.1889.

WILLIAM E. NIGKERSON.

Witnesses:

FRANK G. PARKER, MATTHEW M. BLUNT.

